Apparatus for making pencil leads



May 6, 1941. Y

avJuELss ETAL APPARATUS FOR MAKING PENCIL LEADS 5 sneets-sneet 1 Filed Nov. 11, 1957 INVENTORS @a u in Jue/.rs BY 7*?4 Ehen/.f

' ATTORNEYS May 6, 1941. D. JUELSS ETAL APPARATUS FOR MAKING PENCIL LEADS Filed NOV. l1, 1937 5 Sheets-Sheet 2 Il". Li Ll 1 May 6, 1941- D. JUELss E-rAl.- 2,241,203

APPARATUS- FOR MAKING PENCIL LEADS Y Filed NOV. 1l, 1957 5 Sheets-Sheet 3 INVENTORS @a vl'd Jue/.r4-

BY Tradlf 'Dleur ATTORN EY May 6, 1941.

D. JuELss ET Al.

APPRATUS FOR MAKING PENCIL LEADS Filed Nov'.- 11, 1937 5 Sheets-Sheet 4 INVENTORS nvfJJ/e /rs 17am( Dreh/ ATTORN EYS May 6, 1941. D. JuELss ETAL APPARATUS FOR MAKING PENCIL' LEAp 5 sheets-sheet 5 Filed Nov. 11, 1937 U @um u@ ha |.v AIA, W s s 1 A, Q w A/ Jil. fm Q www im QN imm A .u .6 H www Za k r NNN m J.. b -V www Q, mv M H G im :Patented May 6, 1941 ganzes' of N ew York Appieaassmmsa n, was' sesamstraat I c ciaimso1. 1st-12J d This-invention relates `t'o an apparatus' for" formi-iig rods from plasticmaterials; and'p'articula-rly to improvements" adapted VtoA facilitate' the manufacture of pencil\"leads. Rods of" plastic materials other than those' employed ink pencil leads may be" produced' similarly l`andutilized for a2 variety." of.- purposesl to which they may be" adap'te'di For purposes oifil'lustration; the inven-v tionlwiil Woe* described more "fullyin respect'to its special application totliemanufacture of pencil leads.

`In the production oi pencil'leads'; mixtures con-4 sisting.; essentiallyof.l finely divided" clay` andA graphite with some lwater are, after thorough mixing; formed into elongated "-bodies `or ribbons of shapefan'd dimensions approximating those or anordinary'woodflatl'ii; These'- are inA turn fed to aE maohinewhich periodically severs a portion or pelletfrom'thefendof thebody and extrudes themate'rial, whichisrelatively sti-ii` and-plastic, through a-multiple dieto form the leads. The leads are collected as fformed,andsubjected to a drying` operation whereby water is expelled. After' drying, the-leads areisuiciently hardto permitha-ndling; soithatlthey may lne-packed inretortsandred' This method of `prodauzing penci1- leads, as disclosed in'U. S.-\LettersPaten-ts Nos. 1,362,093, 1,362,094 ari-clv 1,362,095 hasbeen in use-for many years,l although it is not the method commonlyf employed hyf pencil manufacturers.

,The operation as' described produces leads of verysatisfactory andy more uniform y quality than isattainable JoyV othermethods in use, but it is nevertheless relatively-slow and inefficient. The apparatus as used heretofore, either that descriledinthepatents mentioned or the hydraulic or` screw presses commonly used, does not permit suicijent precompressiorrof the material to ensure elimination of occl'uded air, and consequently the leads are not homogeneous. The presence of occluded `airresults in Vnon-u niitrnl distribution ofv waxJ in theA leads whentli latter-are waxed after they havebeen iired; The strength and Writing quality-fof' the l leads is' thus impaired. Also; the mechanism is'H not readily accessible, and'stoppageofthe' opera-tion for any reason sometimesrinvolveslongdelays 'before' production may 'be resumed".y The cost" of l"production' vis consequently relatively high".

. The Ppresentinventionfavoids the diiculties of the previously. known' methods and apparatus, andfprovidesi leadsfof irilrproved quality, particularly `with respect' to' homogeneous "chara'cterA of the lead. Such leads may be usedadvantageou'sly mascot-suenos; *me invention is especially usefulsinpreparing leadsfor mechanical pencils, sincetheyare-strenger and more uniform and thereforeiresisu the-stresser" writing pressure more successfully.' A

It-iislthe objecteofithepreseritPinVentionto providef' arii improved and-more emcient mechanism for-- feedirigand eXtrud-ingn plastic material and` particularly-l for impactingV the material and' reair' and homogeneous -in character. Y

Other objectsland advantages of `the' invention willbe apparent1 asllitisfbe'tterunderstood by referenceoto the followingspecification audaccompanyirig Adrawings,lin'which Fig:- 'lf3 is a' longitudinal f section through the machine on'tlreline' I #I f of FigLQ;

Fig: 2is1 aj'planvietwof thef machine;

. Fig. 3 is-a` frontielevation' of Sth'e machine ;l

Fig. 4 is an enlarged sctionorrtheline 3 4 of Fig.-2;

Fig.Y 5 -is` an-end-viewof 'a"poi^tion "of the machine; o

Fig. 6s is an enlarged plan View of the compression chamber;

Fig. 7 is a section on the line- 'lL-'l of Fig; 9;

10isra sectionfon the line lliof Figi 6;`

Fig. 1l isan elevation of the multiple die; and

rFigl 12isan end view-partial1y in" section of the/discharge mechanismeof the machine.

In order to secure maximum possible efficiency, the machine embodies two separate compression chaiiiliefs, each providedwith a multiple die and duplicate mechanisms 4for feeding and applying pressurefto the'inate'rial'. The application of pressure is ected from 'a single source of power, th'e pressure ramsv being connected' so that pressure is applied alternately in the two compressior-i cha'rilloei"s2` Thusyfor cach rotation of the driving shaft,two-compression cycles are completed,andtlienisliedleads are formed in such a m?ari 'nera"s"'t aordasubstantially continuous op'era-in` Inf-describing the mechanism, therefore', itwil-lloe understoodthat the Various parts areduplcatedon the twosidesu of the machine.

Pressure is applied to the material in a predetermined manner by means of a toggle mechanism actuated positively in both directions by opposed cams designed not only to ensure such positive movement but also to afford rapid movement of the ram dur-ing the major portion of the forward and reverse movement thereof, and relatively slow movement during the period while the material in the compression chamber is under the maximum compression. The "dwell of the ram during the period of maximum com plenlll pSlIiilDS D116 rel'DLVely SlOW SqueeZlIlg 0f the plastic material in the compression chamber as the material is extruded tnroughthe die. iurtnermore, the compression chamber is designed to hold a relatively large quantity of the plastic material, and the portions thereof which have been introduced and are moving forward in the compression chamber are subiected to a slow squeezing action which substantially eliminates all occluded air.V rial Vmaintained in the compression chamber should be at least five and preferably ten to twenty times the amount extruded upon each application of pressure. The air thus expressed escapes rearwardly around the edges of the ram, which has a suiiciently loose fit to permit such elimination. Consequently, the material which approaches the die and is extruded is free from air and is relatively more dense than it would be otherwise, with the result that the extruded lead is of superior quality.

In addition to the features mentioned, the apparatus provides for feeding plastic material positively and in an amount predetermined by adjustment to aord exactly therequired quantity for each forward movement `of the ram, in order to ensure proper pre-compression and the removal of occluded air. The amount of material thus added at each stroke is such that the first effect of the ramis to squash the pellet and thus to remove immediately a large part of the occluded air. The remainder of the air is separated by the squeezing action as the materialis forced forwardly toward the die against the resistanceof the preceding material and the back pressureresulting from frictional resistance of the chamber walls.

The compression chamber and die are constructed to afford complete rigidity and wearresistance, the structure being nevertheless such that it may be readily taken apart so that'any worn or broken parts may be removed and replaced with maximum facility. l

Referring to the drawings, indicates a rigid frame affording a support for the various parts of the mechanism. A source of power, such as a motor 6, is mounted on the frame and is provided with a pulley 1 which drives a pulley 8 through the belt 9. The pulley 8 is mounted on a transverse shaft Iii carrying va pinion II, which in turn drives a gear I2 on a transverse shaft I3, suitably supported in the frame 5. The shaft I3 carries a gear I4 meshing with a pinion I5 which in turn engage/sa gear I6 on a transverse shaft I1, likewise suitably supported in the frame 5. Y Y

The shafts Eiland I1 carry opposed cams I8 and I9 which continuously engage a roller 20 on a pivot 2l which connects the links 22 and 23 forming a toggle.V The link 22 is pivoted at 24 on the frame 5. The link 23 is connected by a pivot,` 25 toa sliding member 25- mounted in suitable guidewaysV in the frame 5. A ram 21 The amount of mate-Y is secured by bolts 28 with a key 29 to the sliding member 2t. One end of the ram 21 proJects into the compression chamber 30. Thus, as shafts i3 and l1 revolve, the cams I8 and I9 shift the toggle and cause the sliding member 2e and the ram 21 to reciprocate. As the toggle is straightened, the rain 21 advances, the cams being so formed that the initialV rate of' advance is comparatively rapid, followed by a slower movement until the stroke is completed,

)whereupon the toggle is broken and the ram is withdrawn at a comparatively rapid rate and then commences another forward stroke. As hereinbefore indicated, the mechanism is duplicated on the two sides of the machine, and one of the rams is retracted as the other advances, permitting alternate compression strokes in the two compression chambers.

Plastic material 3|, in the form of a ribbon, is supported in a chute 32 and is fed positively through an opening 33 in the top of the compression chamber before the ram 21 advances, so that a predetermined amount of the plastic material is sheared from the ribbon and forced into the compression chamber by the ram. The feeding is effected by a rocker arm 34 pivoted at 35 on the frame 5. A roller 36 on the rocker arm engages a cam 31 on the shaft I1, the cam being shaped and positioned so that the rocker arm 34 is lifted after the ram 21 has advanced sufficiently to support the ribbon 3|. At its forward end, the rocker arm 34 has an upwardly projecting arm 38 to whicha gripper 39 is pivoted at 4i). The face of the gripper is adapted to engage the ribbon 3| during the downward movement of the rocker arm 34, forcing the ribben against a shoe 4I which is supported on the arm 34, and to release the ribbon 3l as the rocker arm 34 is lifted. The movement of the gripper 39 is effected by a bar 42 pivotally connected at 43 to the gripper 39 and extending rearwardly to afford an abutment 44. A compression spring 45 is disposed between this abutment and a cross-bar 46 which is mounted 0n the rocker arm 34. The compression spring holds the gripper 39 in position to engage the ribbon 3| except when the spring 45 is compressed. Slots 41 and 48 in the bar 42 permit klongitudinal rmovement thereof, the bar being supported during such movement by the cross-bar 46 and the pin 48'. An arm 49 projects upwardly from the member 25 and is provided with an adjustable screw 50 locked by a nut 5I which is .adapted to engage the abutment 44 as the member 23 advances. The screw 50 is adjusted so that when the ram 21 has severed a section Vor pellet from the ribbon 3l and is in position to support the ribbon, the bar 42 will be moved forwardly -against the spring 45, thus disengaging the gripper 39. As the gripper is disengaged, the rocker arm 34V is lifted by the As hereinbefore indicated, the compressionY chamber is rigidly constructed, but nevertheless is readily accessible, all of its parts being deinountable to permit access and removal or replacement of any broken parts. The compression chamber rests upon a shelf 55, forming a part of the frame 5, to which it is secured by bolts S. The lower block 57 of the compression chamber is held rigidly on the shelf 55 by a key 53, which prevents longitudinal and lateral movement. The bolts 55 extend through openings 56' in the hey 5E?. The upper block 59 is secured to the lower block 5'! by bolts {il} and nuts 5l and by the bolts 5t. Within these blocks, a compression chamber is formed by plates of hardened and resistant steel of any suitable composition, but preferably one embodying nickel and chromium in its composition, to afford hardness and wear resistance. The side plates @2 are held by pins G3 extending through the supporting structure. The lower plate @il is similarly held by pins 65, and the upper plate ii@ is held by pins 61, so that all of the parts are secured against relative movement and rigidly mounted. The die plate St, having a piuraiity of openings (it in the face thereof, through which the material is extruded, is held against the face of the compression chamber by screws 'Iii which extend through the bolts dit, thus locking the bolts against movement and increasing the rigidity of the structure. A bar 'EG' is secured by bolts il to the upper block 59 as a guide for the ram 2.

As pressure is applied to the material in the compression chamber, it is extruded through the die openings in the form of a plurality of rods. The stroke is such that the rods as formed are slightiy long-er than the iinished dimensions. To receive and support the rods as formed and While they are still in a plastic condition, a drum il is supported on a shaft 'l2 project-ing from the key 53 in front of the die plate G8. The drum is provided With a plurality of grooves 73, and at the moment of extrusion ve of these grooves are positioned directly in front of the die opening 59, so that the extruded rods are forced into the grooves. The drum is actuated by a rocker arm 'le having a roller i5 which engages a cam 76 on the shaft I'i. rlne rocher arm 'Hi is secured to a shaft 'il' mounted in a bracket i8 and carries at its end an arm iS pivoted at B on the frame 5 and connected by a link 8l to a bell crank lever E2, loosely mounted on the shaft 12. The bell crank lever carries` a pawl 83 which engages a ratchet t4 secured to the shaft 12. The cam 3S is formed so that upon the completion of the stroke of the ram which has forced the rods from the die into the grooves 'i3 of the drum ll the pawl 33 is actuated to advance the drum li in the direction of the arrow, thus removing the finished product from the die plate. A shield d5 extends part way about the drum, so as to support the rods until they are carried to the point Where they may be discharged. An electric heating element 3G is connected to the shield d and adapted to be supplied with current from a source of power so that the shield is heated by conduction and the temperature is raised to prevent condensation of moisture and possible stiel;- ing of the extruded rods in the grooves i3.

As indicated, the rods as formed are slightly longer and project from the grooves at the front of the drum li. To remove the projections, a knife Si' is supported on the shield 85 with its edge bearing against the face of the drum 1I. As the drum rotates, the ends of the rods are shea-red flush with the face of the drum, and the parts removed are discharged through a chute 83.

As the rods in the grooves 'i3 reach the lower edge of the shield 85, they drop, one by one, upon a conveyor consisting of a series of rollers 89 connected by linlcs at their ends to form a continuous conveyor Which passes at one end over asprociret Sil supported on a shaft si, and at the other endover a similar sprocket g2 supported on a shaft 93. The shaft S3 carries a sprocket 54 which is connected by a chain 95 to a sprocket 96 on a shaft 97. A Worm gear t on the shaft 9i is driven by a worm 99 on a shaft ld. The shaft H59 carries a sprocket itl and is driven by a chain |02 from a sprocket m3 on the drive shaft of the motor G. The movement of the rollers 89 forming the conveyor is timed With respect to the rotation of the drum li, so that as each rod falls from thedrum 'ii it is between two adjacent rollers SS and is conveyed thence to the discharge end of the conveyor.

A chamber |94, which is supplied With any suitable heating medium, preferably steam, through a pipe M25 having a valve 96, is disposed beneath the upper night of the conveyor, and supplies heat to the conveyor and to the rods disposed thereon, so as to continue the removal of moisture from the rods as they are advanced. From the rollers $59, the rods may be discharged upon any other suitabie mechanism to continue the drying operation until the rods are suiiciently stiff to permit handling thereof.

In describing the operation of discharging the rods from the die plate, I have referred to the elements of a single mechanism for that purpose, but as already pointed out, the mechanism is duplicated so that the rods formed by the alternate compressions in the two compression chambers are similarly delivered to the rollers @il forming the conveyor. The operation of the conveyor is timed with respect to the discharge of the rods, so that rods formed and delivered at `the two sides of the machine fall upon the conveyor in such a Way as not to interfere.

Because of the utilization of power through the application of pressure in alternate pressure chambers during rotation of the drive shaft, the operation is speeded up and the output of the machine is markedly increased. A very important advantage results from the method of feeding the material positively and in predetermined amounts, and in maintaining within the compression chamber a relatively large quantity of the material which is subjected repeatedly to pressure, thereby removing occluded air before the material approaches the die openings. The resulting homogeneity of the product is particularly noticeable. The application of the toggle and the positive operation thereof permits control of the movement and particularly the application of pressure which is maintained for a suflicient period tol thoroughly compress` the material, thereby facilitating the removal of air. The inclusion in the die chamber of a Considerable amount of material increases the back pressure, due to frictional resistance of the chamber Walls, which is overcome by the controlled application of pressure through the toggle mechanism. These and other advantages result in substantial improvement of the operation and reduction of the cost of producing rods of plastic material adapted for use as pencil leads and for numerous other purposes.

Various changes may be made in the form, construction and arrangement of the parts, as Well Vas the details of the operation as described, without departing from the invention or sacrificing any of its advantages.

We claim:

1. An apparatus for forming rods from plastic material comprising a compression chamber having anV extrusion orifice, a ram reciprocably mounted inthe chamber and means for actuating the ram including toggle means and cams at opposite sides of the toggle means and directly bearing on the knee thereof for positively actuating the toggle means to reciprocate the ram, and means for rotating the cams.

2. An apparatus for forming rods from plastic material comprising a compression chamber having an extrusion orifice, a ram reciprooably mounted in the chamber and means for actuating the ram including toggle means and cams at opposite sides of the toggle means and directly bearing on the knee thereof for positively actuating the toggle means to reciprocate the ram, and means for rotating the cams at a uniform speed, the shape of the cams being such that the initial rate of advance of the ram is comparatively rapid and the later rate of advance is slower. Y

3. An apparatus for forming rods from plastic materials comprising a pair of substantially parallel compression chambers each having an eX- trusion orifice, a ram reciprocably mounted in each of said chambers, means for positively actuating the rams so that one advances as the other is retracted, including toggle means and cams at opposite sides of the toggle means and directly bearing on the knees thereof, and means for rotating the cams.

4. An apparatus for forming rods from plastic material comprising a compression chamber having an extrusion orifice, a ram reciprocably mounted in the chamber and means for actuating the ram including toggle means comprising a pair of toggle arms, a pivot prin connecting said arms and a roller mounted on said pivot pin and cams at opposite sides of the toggle means and directly bearing on said roller for positively actuating the toggle means to reciprocate the ram, and means for rotating the cams.

5. An apparatus for forming rods from plastic material comprising a compression chamber having an opening through which a ribbon of plastic material may be fed and an extrusion orice, a ram reciprocably mounted in the chamber,

means for reciprocating the ram, mechanical means for gripping the opposite sides of a ribbon of plastic material for feeding it to and through said opening and into said compression chamber including parts spaced opposite one another, means for causing one of said parts intermittently to move toward the other part to grip the ribbon of material, said parts thereafter moving said ribbon of material towards said compression chamber, means for causing said parts to release said ribbon of material after a predetermined movement toward the compression chamber and means for restoring said parts to their original position to again grip the ribbon of material on a subsequent feeding operation, and means so synchronizing the operation of said feeding means and the operating means therefor with the reciprocatio-n of said ram that the feeding means is operated to feed material to said chamber only between compression strokes of the ram.

6. An apparatus for forming rods from plastic material comprising a compression chamber having an opening through which a ribbon of plastic material may be fed and an extrusion orifice, a ram reciprocably mounted in the chamber and means for reciprocating the ram including toggle means and cams at opposite sides of the toggle means and directly bearing on the linee thereof for positively actuating the toggle means to advance and retract the ram; means for rotating the cams; mechanical means for gripping the opposite sides of a ribbon of plastic material for feeding it to and through said opening and into said compression chamber including parts spaced opposite one another, means for causing one of said parts intermittently to move toward the other part to grip the ribbon of material, said parts thereafter moving said ribbon of material towards said compression chamber, means for causing said parts to release said ribbon of material after a predetermined movement toward the compression chamber and means for restoring said parts to their original position to again lgrip the ribbon of material on a subsequent feeding operation, and means so synchronizing the operation of said feeding means and the operating means therefor with the reciprocation of said ram that the feeding means is operated to feed material to said chamber only between compression strokes of the ram.

DAVID JUELSS. FRANK DREWS. 

